CD133, also known as prominin-1 and several other designations, is a glycoprotein known to be expressed in several types of stem cells, including hematopoietic stem cells, endothelial progenitor cells and neural stem cells. CD133 was found to be present or enriched in cell populations found in several human solid tumors, such as colon carcinoma, melanoma and brain tumors (for example, glioblastoma). Currently, CD133 is considered to be a putative marker for cancer stem cells (CSCs), which are cancer cells possessing stem-cell like characteristics, namely, an ability to differentiate into multiple-cell types, and the ability to give rise to new tumors. CD133 protein was found to localize to membrane protrusions and to be often expressed on adult stem cells. One proposed function for CD133 is maintenance of“stemness” through suppression differentiation.
Anti-CD133 monoclonal antibodies (mAbs) are an important tool in the areas of CD133 studies and detection, as well as in the areas of cancer studies, cancer detection, diagnostics and treatment, and other related fields. Available anti-CD133 monoclonal antibodies suffer from a number of deficiencies. For example, most of the early published work in the field of CD133 studies was carried out with monoclonal antibodies recognizing epitopes of CD133 that may have been glycosylated and became undetectable during cell differentiation. Other known monoclonal antibodies did not recognize certain posttranslationally modified forms of CD133. Some examples of anti-CD133 monoclonal antibodies recognized only unglycosylated CD133 epitopes, but not their glycosylated form and vice versa. In some other examples, anti-CD133 monoclonal antibodies were shown to be useful only in a limited range of biological assays. Accordingly, there is a need for anti-CD133 monoclonal antibodies that recognize a range of CD133 variants and isoforms with high specificity, regardless of the protein's glycosylation state or other posttranslational modifications, and are useful in a variety of applications. There is also a need for methods of producing such antibodies.